This invention relates to a crankshaft bearing assembly. More particularly, it relates to a crankshaft bearing assembly for a fluid-machine comprising reciprocating components, wherein the crankshaft bearing assembly comprises a shaft with a co-rotating first eccentric surrounded by a second eccentric, wherein the second eccentric is adjustable around the first eccentric, and wherein the second eccentric is surrounded by a bearing and a crankshaft bearing housing, the second eccentric being connected, by means of a coupling, to a shaft sleeve concentrically rotatable around the shaft.
In this context, a reciprocating fluid-machine implies pumps and motors. The term reciprocating fluid-machine is used to include diaphragm pumps as well as piston pumps and piston motors. Hereinafter, reference is made to pumps, insofar as the adjusting mechanism appears to be of most relevance to pumps.
Relatively frequently, a need arises for allowing the fluid flow through a pump to be adjusted, even though the pump is run at a constant rotational speed, for example by means of an electric cage induction motor. When it comes to the dosing of a fluid, it is also of importance to be able to pre-set the pump at a given fluid flow at a given rotational speed.
U.S. Pat. No. 5,588,339 discloses a pump in accordance with the above introduction, in which a cross-slotted coupling is disposed between the shaft sleeve and the second eccentric for allowing the second eccentric to be adjusted relative to the first eccentric. A cross-slotted coupling is incompatible with accurate adjustment when transmitting large forces.
WO document No. 2004/053345 discloses a crankshaft bearing assembly designed to impart a lower speed to the piston of an internal combustion engine when at the top dead centre than when at the bottom dead centre.